fish_of_the_worldfandomcom-20200213-history
Heterodontus francisci
Heterodontus francisci (''Horn shark)' Kingdom: '''Animalia Phylum: Chordata Class: Chondrichthyes Order: Heterodontiformes Family: Heterodontidae Genus: Heterodontus Species: Heterodontus francisci Environment: milieu, climate zone, depth range, distribution range: Marine; demersal; depth range 0 - 152 m, usually 2 - 11 m. Subtropical; 37°N - 15°S, 124°W - 75°W. Distribution: Eastern Pacific: central California, USA to the Gulf of California, and probably Ecuador and Peru. Size, weight, age: Max. length: 1.22 m, common length: 97 cm; weight: ?'''; age: '''12 years Short description: Like other bullhead sharks, the horn shark has a short, wide head with a blunt snout and prominent supraorbital ridges over the eyes. The horn shark's supraorbital ridges are low and terminate abruptly; the space between them on top of the head is deeply concave. Each eye lacks a nictating membrane and is followed by a tiny spiracle. The nostrils are split into inflow and outflow openings by a long flap that reaches the mouth. The inflow openings are encircled by a groove, while another groove connects the outflow openings to the mouth. The mouth is small and curved, with prominent furrows at the corners. There are 19–26 tooth rows in the upper jaw and 18–29 tooth rows in the lower jaw. The teeth at the front of the jaws are small and pointed, with a central cusp flanked by a pair of lateral cusplets; those at the sides of the jaws are much larger, elongated lengthwise, and molar-like. The body is cylindrical, with two high, somewhat falcate (sickle-shaped) dorsal fins bearing stout spines at the front. The fin spines of reef-dwelling horn sharks are shorter than those living in algal habitats, as their spines become worn down on rocks from the sharks' movements. The first dorsal fin originates over the bases of the large pectoral fins, while the second dorsal fin originates slightly anterior to the free rear tips of the pelvic fins. The caudal fin has a short lower lobe and a long, broad upper lobe with a strong notch near the tip. The horn shark's dermal denticles are small and smooth, numbering some 200/cm2 on the back in adults. The dorsal coloration consists of various shades of gray or brown with many small dark spots, though these may be absent in older sharks; the underside is yellowish. There is a dark patch of small spots below the eye. This species may reach a length of 1.2 m (3.9 ft), though most individuals do not exceed 1 m (3.3 ft). Biology: Sluggish, nocturnal, and mostly solitary species. Inhabit rocky bottoms, kelp beds, sandy draws between rocks, on sand flats, deep crevices and small caves and also large underwater caverns. Adults tend to return to the same resting place every day. Feed on benthic invertebrates, especially sea urchins, crabs and probably abalone, also fishes. Oviparous. May bite back when harassed. Has broad muscular paired fins used as limbs for clambering on the bottom. Catch reduced to fish meal; fin spines used in production of jewels. Life cycle and mating behavior: Oviparous. Distinct pairing with embrace. Courtship starts when the male chases the female, then when both are ready, they drop to the bottom. During courtship and prior to copulation, the male bites and wraps its body to the female pectoral fin, body, tail, and gills. The male then inserts a single clasper in the female's cloaca; copulation lasts 30 to 40 min. After one or two weeks later, the eggs are laid in about 11 to 14 intervals for 4 months which were deposited under rocks or in crevices, as was observed in nature. In captivity, the female drops the eggs on the bottom where the contents of the egg cases maybe eaten by these sharks; the eggs are hatched in 7 to 9 months. The young begin to feed one month after hatching. Main reference: Compagno, L.J.V., 2001. Sharks of the world. An annotated and illustrated catalogue of shark species known to date. Vol. 2. Bullhead, mackerel and carpet sharks (Heterodontiformes, Lamniformes and Orectolobiformes). FAO Spec. Cat. Fish. Purp. 1(2):269 p. FAO, Rome. IUCN Red List Status: DATA DEFICIENT (''DD)' '''CITES: Not Evaluated CMS: Not Evaluated Threat to humans: Traumatogenic Human uses: Fisheries: minor commercial; aquarium: public aquariums. Category:Heterodontidae, Bullhead, horn, or Port Jackson sharks